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authorBart Van Assche <bvanassche@acm.org>2018-09-26 14:01:04 -0700
committerJens Axboe <axboe@kernel.dk>2018-09-26 15:11:28 -0600
commitcd84a62e0078dce09f4ed349bec84f86c9d54b30 (patch)
tree2cdd58e3abebc23c86351ca12815b751a62bdc1a /drivers
parentbca6b067b0b269a7b8ba129e2a918309ca8b4a55 (diff)
block, scsi: Change the preempt-only flag into a counter
The RQF_PREEMPT flag is used for three purposes: - In the SCSI core, for making sure that power management requests are executed even if a device is in the "quiesced" state. - For domain validation by SCSI drivers that use the parallel port. - In the IDE driver, for IDE preempt requests. Rename "preempt-only" into "pm-only" because the primary purpose of this mode is power management. Since the power management core may but does not have to resume a runtime suspended device before performing system-wide suspend and since a later patch will set "pm-only" mode as long as a block device is runtime suspended, make it possible to set "pm-only" mode from more than one context. Since with this change scsi_device_quiesce() is no longer idempotent, make that function return early if it is called for a quiesced queue. Signed-off-by: Bart Van Assche <bvanassche@acm.org> Acked-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Ming Lei <ming.lei@redhat.com> Cc: Jianchao Wang <jianchao.w.wang@oracle.com> Cc: Johannes Thumshirn <jthumshirn@suse.de> Cc: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/scsi/scsi_lib.c11
1 files changed, 7 insertions, 4 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index eb97d2dd3651..62348412ed1b 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -3046,11 +3046,14 @@ scsi_device_quiesce(struct scsi_device *sdev)
*/
WARN_ON_ONCE(sdev->quiesced_by && sdev->quiesced_by != current);
- blk_set_preempt_only(q);
+ if (sdev->quiesced_by == current)
+ return 0;
+
+ blk_set_pm_only(q);
blk_mq_freeze_queue(q);
/*
- * Ensure that the effect of blk_set_preempt_only() will be visible
+ * Ensure that the effect of blk_set_pm_only() will be visible
* for percpu_ref_tryget() callers that occur after the queue
* unfreeze even if the queue was already frozen before this function
* was called. See also https://lwn.net/Articles/573497/.
@@ -3063,7 +3066,7 @@ scsi_device_quiesce(struct scsi_device *sdev)
if (err == 0)
sdev->quiesced_by = current;
else
- blk_clear_preempt_only(q);
+ blk_clear_pm_only(q);
mutex_unlock(&sdev->state_mutex);
return err;
@@ -3088,7 +3091,7 @@ void scsi_device_resume(struct scsi_device *sdev)
mutex_lock(&sdev->state_mutex);
WARN_ON_ONCE(!sdev->quiesced_by);
sdev->quiesced_by = NULL;
- blk_clear_preempt_only(sdev->request_queue);
+ blk_clear_pm_only(sdev->request_queue);
if (sdev->sdev_state == SDEV_QUIESCE)
scsi_device_set_state(sdev, SDEV_RUNNING);
mutex_unlock(&sdev->state_mutex);